1. Field of the Invention
This invention relates to an aerosol valve having means to cut off the discharging flow when the container is tipped.
There has always been a need to cut off discharging flow when an aerosol can is tipped. The need is greater now. With the environmentally mandated prohibition of chloroflorocarbons and hydrocarbons propellants, the aerosol industry bas turned to pressurized gas propellants, especially nitrogen and carbon dioxide. Nitrogen and other pressurized gases, having relatively high vapor pressure, are not as ideal as some chloroflorocarbons or hydrocarbons because they do not change from liquid phase to gaseous phase and permit the pressure to recover as part of the propellant is used up or lost. Nitrogen and carbon dioxide do not go into liquid phase at practical pressures used in aerosol containers.
To permit the tilting of the container during dispensing runs the risk of the bottom of the dip tube being exposed to the head space above the liquid which would let the pressurized gas above the product escape. Any such escape cannot be tolerated a compressed gas system.
2. Description of Related Art including Information Disclosed under .sctn..sctn.1.97 to 1.99
While the aerosol valve art is extensive, there is no satisfactory answer to the problem described above.
The U.S. Pat. No. to Braun 3,315,693 which issued Apr. 25, 1967, discloses an attachment structure in which a gravity-responsive ball normally blocks a passage in an aerosol valve to the outside of the valve body, but, when the can is inverted, the ball drops to permit passage of the product into the valve body. With the valve body filled with and submerged in product, there is no way for the gas pressure in the head space to escape, and it performs its normal function of pressuring the product out through the valve outlet. This is an example of an "invertible valve".
There are other examples of such structures, one being the U.S. Pat. No. 4,728,692 to Meurescb et al issued Feb. 9, 1988. In this patent a one-piece valve body with conventional appearance from the outside has an inside chamber for a ball-operated valve also accessible to the outside of the valve body for when the aerosol can is inverted. The operation is the same as in the Braun structure.
In U.S. Pat. No. 2,954,904 which issued Oct. 4, 1960 to Potoczky an overcap is provided which connects to the aerosol valve stem by way of a flexible diaphragm under a flexible top panel of the cap. A ball is disposed between the diaphragm and the top panel, both the diaphragm and top panel being downwardly inclined toward their centers. In normal vertical disposition of the can, the ball rolls toward the center of the overcam immediately above the stem, and when it is desired to operate the aerosol valve therebelow, below, one merely presses the center of the overcap top panel and the depressing force acts through the ball to depress the center of the diaphragm and the valve stem. Such an arrangement is fine for assuring that the can be vertical when the aerosol is operated. However, it does not serve to function as a cut-off if the operation is commenced while the can is vertical and the can is then tilted to a position, say, where the bottom of the dip tube is exposed to the head space.
Another U.S. Pat. No. 3,186,605 to Potoczky issued Jun. 1, 1965 shows a functionally similar but differently structured arrangement.